well, if I don't have kids, I pay more. I'm no tax scholar, and I guess the IRS doesn't call it a "penalty," but in the real world that sounds like a penalty to me. If I don't have a kid, then I pay more. And if I refuse to pay more, I go to jail.
I know, that's a stretch. But still.
So let's take the scenario where I don't want to buy insurance. Under the new bill, now I have to pay this excise, or "penalty."
Now, on the other hand, let's take the scenario where there is a mandatory tax to support a single-payer, government-provided insurance. In either case, I am paying a tax/penalty. I can see how one is philosophically different than the other, but in the end, it amounts to the same thing; I'm sending the government money.